[pickers] Fix onAccept not being called after external value change

[michelengelen]

This PR fixes a bug where the onAccept callback (and consequently the Clear action in the picker's action bar) would fail to fire if the picker's value had been updated externally (e.g., via a controlled value prop from Redux or parent state) since the last time the picker was opened or a value was committed.

Fixes #21962

[code-infra-dashboard]

Bundle size

Bundle	Parsed size	Gzip size
@mui/x-data-grid	0B(0.00%)	0B(0.00%)
@mui/x-data-grid-pro	0B(0.00%)	0B(0.00%)
@mui/x-data-grid-premium	0B(0.00%)	0B(0.00%)
@mui/x-charts	0B(0.00%)	0B(0.00%)
@mui/x-charts-pro	0B(0.00%)	0B(0.00%)
@mui/x-charts-premium	0B(0.00%)	0B(0.00%)
@mui/x-date-pickers	🔺+63B(+0.03%)	🔺+12B(+0.02%)
@mui/x-date-pickers-pro	🔺+63B(+0.02%)	🔺+12B(+0.02%)
@mui/x-tree-view	0B(0.00%)	0B(0.00%)
@mui/x-tree-view-pro	0B(0.00%)	0B(0.00%)

Details of bundle changes

Deploy preview

https://deploy-preview-22131--material-ui-x.netlify.app/

---

Check out the code infra dashboard for more information about this PR.